1. Field of the Invention
The present invention is in the field of hydraulic accumulator devices and relates more particularly to an accumulator device especially useful as a pulsation dampener in situations where pulses of wide frequency range are encountered. The invention is further in the field of an dampener of the type described which may be used in high temperature applications and in conjunction with aggressive liquid materials.
2. The Prior Art
It is conventional to incorporate pulsation dampener devices in hydraulic systems as a means for reducing the amplitude of pulses generated, for instance, in pumping apparatuses associated with the system.
In the undampened systems of the type described the pulses generated may have deleterious effects on components downstream of the pump, and if the pulses are at a frequency which happens to resonate with elements of the system, actual damage may result to conduits and other components of the system.
Representative examples of pulsation dampeners of the type described which are effective over a wide frequency range may be found in U.S. Pat. Nos. 3,509,916; 3,920,047 and 3,930,521. Such devices typically comprise a pressure vessel having at one end a gas charging port and at the other end an oil port for the admission of hydraulic fluid or other liquids which are treated by a pump and are, thus, subject to surges in pressure as resulting from the cycles of the pump, etc.
The pressure vessel is typically divided into two chambers which are isolated from each other by a distensible bladder member which, where the pressure in the gas chamber exceeds that of the oil chamber, forces oil through the oil port of the pressure vessel. Where the pressure in the hydraulic system exceeds that in the gas chamber, fluid is admitted into the oil chamber, further compressing the gas in the bladder and storing energy therein, which stored energy is released to the fluid when the hydraulic pressure drops to a value below the gas pressure. Bladder type accumulators of the type described are, to a degree, capable of dampening pressures through a wide frequency range.
Since, for the successful operation of such prior art devices, it is necessary to employ a stretchable bladder it will be readily recognized that the choice of materials of which the bladder may be comprised is quite limited, such materials typically comprising an elastomeric substance such Buna rubber or the like.
However, the use of pulsation dampeners of the type described cannot be attempted in connection with liquids at temperatures higher than the tolerance temperatures of the elastomeric bladder as the bladder would be rapidly destroyed. Similarly, where the liquid is corrosive to the bladder or incorporates entrained granular material, conventional bladder type accumulators are likewise unacceptable.
In a further type of accumulator, the oil and gas chambers may be separated by a rigid piston member sliding in a cylindrical bore defined by the pressure vessel. While such piston type dampener may effectively resist the corrosive action of hot or aggressive liquids, and also may be effective in dampening low frequency, high amplitude pulses, the same is generally ineffective where high frequency pulses are encountered due to the large inertia of the piston.